WO2003055152A1 - Protocole de communication en serie a schema de fonctionnement maitre- esclave - Google Patents

Protocole de communication en serie a schema de fonctionnement maitre- esclave Download PDF

Info

Publication number
WO2003055152A1
WO2003055152A1 PCT/ES2001/000423 ES0100423W WO03055152A1 WO 2003055152 A1 WO2003055152 A1 WO 2003055152A1 ES 0100423 W ES0100423 W ES 0100423W WO 03055152 A1 WO03055152 A1 WO 03055152A1
Authority
WO
WIPO (PCT)
Prior art keywords
frame
slave
nodes
node
bus
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
PCT/ES2001/000423
Other languages
English (en)
Spanish (es)
Inventor
Ernest Gil Dolcet
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Universitat Rovira i Virgili URV
Original Assignee
Universitat Rovira i Virgili URV
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Universitat Rovira i Virgili URV filed Critical Universitat Rovira i Virgili URV
Priority to PCT/ES2001/000423 priority Critical patent/WO2003055152A1/fr
Publication of WO2003055152A1 publication Critical patent/WO2003055152A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

Links

Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L12/00—Data switching networks
    • H04L12/28—Data switching networks characterised by path configuration, e.g. LAN [Local Area Networks] or WAN [Wide Area Networks]
    • H04L12/40—Bus networks
    • H04L12/403—Bus networks with centralised control, e.g. polling

Definitions

  • the present invention refers to a protocol or method of serial communication (terms used interchangeably throughout the text) with a master-slave type of operation scheme, ie master-slave, optimized for an architecture based on a microcontroller equipped with a UART for each node, whether master or slave, whose master node always acts as a primary station and slave nodes as secondary stations and where the communication path planning consists of a distribution of messages that circulate through said pathway, generally formed by a set of groups of data transfer messages including at least one write message from the master node to a slave node, followed by, optionally, a read or reply message from the same node, chained from successively forming a normal cycle of communication,
  • the proposed method is especially suitable for an internal communication system of a car and for industrial distributed control systems, although its application should not be considered restricted to any of the aforementioned areas.
  • the invention also concerns a medium readable by a computer coded with a program for the construction of special frames used in the method, as well as a medium readable by a computer coded with a program to perform a method of planning for temporary use of a bus according to the criteria set forth by the invention.
  • Non-critical applications (). Presentation of data to the driver, communication between electronic equipment (air conditioning, audio, mirrors, diagnosis, etc.).
  • a fourth class (class D) can also be considered, covering high-speed systems for applications, for example multimedia (> 1Mbit / s).
  • the contention procedure of this protocol limits its maximum operating speed.
  • the SAE J1850 protocol was approved by the SAE in 1998 and finally revised in 1994. It is a protocol that, to some extent, comes from the Chrysler CCD protocol. Its specification includes layers 1 and 2. Its main contribution was the inclusion of the responses of the recipient nodes within the frame itself emitted from the origin node. Specifically, it allows: one-byte response from a single recipient, concatenated one-byte responses from multiple recipients, and multi-byte response from a single recipient.
  • the ANC method changes, which in this case, to govern 32 nodes is forced to treat them as two logical buses of 16 nodes separately.
  • the physical layer of this version uses NRZ coding, with start-stop synchronization both in the ANC zone and outside it. This synchronization consists of sending, from the frame sending node, 2 synchronization bits every 4 bits of the frame. The type of channel used is twisted pair.
  • the high speed version requires the use of shielded twisted pair.
  • the physical layer it uses NRZ as with start-stop synchronism in the ANC zone, but outside it uses NRZ with bit stuffing (inserting a bit of the opposite sign if 5 consecutive bits do not change in value), just like CAN. The number of nodes is reduced to 16.
  • this protocol adds a new query method with response chained multiple nodes within the same frame called SDG (Simultaneous Data Gathering).
  • SDG Simultaneous Data Gathering
  • the SDG procedure allows a series of responses from other nodes to be concatenated in an original frame followed by a CRC field of the origin node and the subsequent individual concatenated (ACK bit) confirmation of the response nodes.
  • the CRC field protects the frame from its beginning until the last response inclusive.
  • SDG allows a substantial saving of time in data collection, although it must be taken into account that it only allows consultation from the original node and not the sending of data.
  • TTP Time Triggered Protocol
  • H. Kopetz of the University of Vienna appeared towards 1994, represented a very high qualitative leap with respect to the communication buses of that time and several versions were made covering all classes SAE A, B and C: TTP / A, TTP / B and TTP / C.
  • TTP uses the TDMA method (Time-Division Multiple Access) based on a temporary message planning as access to the medium.
  • this protocol can be considered as the first one that broke the communications trend of this field so far based on the bus planning for ET events (event triggered), planning the TT time planning (Time Triggered ).
  • the operation of the bus is cyclic.
  • the moment of access to the bus in each cycle, by a node, is determined by the contents of the MEDL table (MEssage Description List) located in each node.
  • MEDL table MEssage Description List
  • Each node has an internal clock, updated by a resynchronization frame sent with a certain frequency by a node, which allows considering the existence of a global clock.
  • Temporary planning also allows you to ensure determinism in the different temporary replicas of the value of a set of variables throughout the system (if an error has not occurred).
  • the speed of this bus of 1 Mbit / s (TTP / C) although since 1994 a version was notified to 2 Mbit / s in 1997 and another one was announced at 10 Mbit / s, which makes it a clear candidate for systems of Real time critical security applications.
  • the X-by-wire concept comes from the aeronautical industry consisting of the replacement of mechanical or hydraulic systems with wired systems, with electronic control and communication systems requires a highly reliable communication system and the trigger for its approach has been the high fault tolerance of the TTP protocol mentioned above.
  • the Qwik protocol was the result of a thesis developed at the Chalmers University of Technology and is described in "Technical Specification Qwik Sigma-1.2 Node", QED AB, 1997. It is oriented to simple applications (input / output), of non-critical safety, and with low speed requirements and was applied to the sensing of switches in the steering column of a vehicle. His main contribution is his simplicity and the symbols used.
  • QWIK is a bit-oriented, cyclic type protocol.
  • a pulse train sent by the master node is also used, with a minimum separation between them, if there are no messages to be transmitted by the slave nodes. If any of it has a message to send, it identifies its slot by means of the pulse count and, once found, transmits the frame, so that the space between synchronization pulses of said slot is dilated.
  • This protocol affects the OSI (Open Systems Interconnection) layers 1 and 2. It is based on the method of access to the master / slave bus, with a single master, for which it does not need any arbitrary procedure. Because of this, you can guarantee the Message transmission latencies.
  • the frame used is character oriented, so that the protocol can be implemented based on a microcontroller equipped with a UART.
  • An important feature is the frame used, which, in its initial part, has a character that allows to resynchronize the clock of the communication system of the receiving node for the rest of the frame. This implies the possibility of using a low precision internal oscillator ( ⁇ 15%) integrated in the microcontroller, instead of an external crystal. This resynchronization allows the precision to be tuned to 0.5%, sufficient for its operation.
  • TP Twisted Pair
  • STP Shielded Twisted Pair
  • SW Single BS Cable: Manch Bit Fill: Manchester
  • the ModBus protocol developed by the Modicon company. It is an open protocol, whose implementation can be done by software (on a microcontroller for example) and using a UART. Its specification covers layer 2 and layer 7. As a physical layer, the well-known RS485 standard can be used, among others.
  • the method of access to the bus is of the master / slave type. The master node can perform point-to-point transactions with a slave node, or send broadcast messages to the entire bus. If an error is detected in the reception in the slave node, it sends a response message indicating the type of error.
  • the protocol has two types of frames: frames based on ASCII characters and binary frames.
  • frames based on ASCII characters To solve the problem of transparency of data in binary frames, the protocol imposes some intervals of silence at the beginning and end of the frame, as well as a maximum interval between characters of half a character.
  • the frame does not have a data length field. This information is considered inherent in the command field.
  • the meaning of the command field corresponds to layer 7.
  • ModBus defines a series of commands, with the number of characters and associated meaning. This protocol has been extended throughout the industrial sector in low security applications. The operating speed is 19.2 kbit / s.
  • the invention concerns a serial communication method with master-slave operation scheme, optimized for a microcontroller-based architecture equipped with a UART for each node, whether master or slave, whose master node always acts as a station primary and slave nodes as secondary stations and where the planning of the communication route consists of a distribution of messages that circulate in said way, generally formed by a set of groups of data transfer messages including at least one message writing from the master node to a slave node, followed by, optionally, a read or reply message from the same node, chained successively forming a normal communication cycle and said method is characterized by understanding the use of special frames of consultation, of various types, which are intended to be interspersed between said groups of m testing, where necessary from the point of view of the application, generating queries or a supervisory action capable of reaching all nodes to detect from the master node if in any of these slave nodes there is an urgent situation that requires immediate attention by the master node, with the possibility that said special frames are used, in other operating schemes,
  • the method is applied in a bus topology, for the control and management of the status of a plurality of slave nodes connected to a master node through at least one bus, operating within a bus system.
  • communication that offers the media access services used for sharing the data communication bus between multiple nodes, and other functionalities required for the exchange of serial information, serialization / deserialization, interaction with the local user of the communication system and the interaction with a physical layer.
  • the resolution of the transfer of information between the master node and the slave nodes according to the proposed method is essentially due to three forms of operation: cyclic data messages; - acyclic messages of low priority data; and acyclic, sporadic, high priority data messages.
  • the mentioned interleaved inclusion of said special query frames is carried out which, in case of detecting a request for attention, in At least one of the aforementioned slave nodes causes attention of the master node with point-to-point data transfer messages that can be included by two procedures: an extension of the communication cycle, if justified by urgency or a change Consistently in a switching to an operation based on an emergency cycle appropriate to the case.
  • the method proposes a mechanism consisting of a continuous query loop from the master node based on the use of one or more of the aforementioned special query frames, consecutive, until the detection of one or more requests for attention, in which case they are attended, through the use of data frames, to subsequently continue with the query frames.
  • bus planning can be constituted by an integration of cyclic data transfer intervals together with reserved query intervals for the detection of low priority attention requests, made by including said special frames in said intervals and the corresponding attention through data frames.
  • the method proposes to use reserved intervals for cyclic messages and reserved intervals for low priority acyclic messages, and where the first ones are also subject to the periodic inclusion of special query frames. to detect high priority care requests.
  • special frames of various types, are the following:
  • SingleSlot frame consisting of a single slot or temporary response window of the slave nodes dedicated to the detection of requests for attention of said nodes without identifying which or which request;
  • MultiSlot frame consisting of multiple slots or temporary response windows of the slave nodes, dedicated to the detection of requests for attention of said nodes identifying which or which request;
  • SlotContention frame or slot contest consisting of a certain number of slots or temporary response windows, whose purpose is to detect the highest priority attention request present on the bus, identifying which node it comes from and with what priority it issues it.
  • all said special frames have in common the meaning of the A / C and extra fields of the first frame byte, whose fields in addition to being part of the header, identify the type of frame in question and because the Slot type frames are all composed of four consecutive parts: a.- frame header formed by at least one initial byte, which contains the frame type indicator field and an extra field; b.- interval of change to answer mode; c- response interval consisting of temporary response windows, and d.- response mode output interval.
  • intervals b, c, and d are predetermined by temporary values known by all bus nodes, stored in tables resident in each of the nodes such that the intervals b, c, and d are predetermined by some Temporary values known by all bus nodes, stored in resident tables in each of the nodes.
  • Fig. 1 shows schematically the operation of a master / slave configuration.
  • Fig. 2 illustrates a possible physical appearance of the minimum configuration of a node.
  • Fig. 3 shows the format of the first byte of all frames.
  • Fig. 4 is illustrative of the normal frame format with indication of the length of each field.
  • Fig. 5 shows the format of the Byte frame (coincident with Fig. 3, being formed by a single byte).
  • Fig. 6 exemplifies the procedure of interaction of the master-slave nodes according to the SingleSlot frame, with a bus that includes two slave nodes.
  • Fig. 7 exemplifies the procedure of interaction of the master-slave nodes according to the MultiSlot frame in a bus with N slave nodes.
  • Fig. 8 is equivalent to the previous one, although it shows the operation of the MultiSlot frame in the case of an asynchronous version.
  • Fig. 9 illustrates the MultiSlot frame structure on a bus with N slave nodes and with character-oriented response mode
  • Fig. 10 exemplifies the procedure of interaction of master-slave nodes according to the SlotContention frame.
  • Fig. 11 shows as an example the procedure for executing a service such as SendPPUDR (which will be explained later).
  • Fig. 12 shows a static bus planning based on a service
  • Fig. 13 is a time diagram illustrating a static bus planning based on SendPPUDR services from an example with three groups of nodes.
  • Fig. 15 shows a static bus schedule with message period ⁇ low cycle + dynamic period + low priority.
  • Fig. 16 illustrates a static bus planning (multi-period) + sporadic dynamic of high priority AR_evPoll.
  • Fig. 17 is equivalent to the previous one, but with attention detection in an evPoil AR query.
  • Fig. 18 shows a static bus planning (multi-period) + sporadic dynamic of high priority AR_nPoll.
  • Fig. 19 is equivalent to the previous one but with attention detection in an AR nPoll query.
  • Fig. 20 shows a static bus planning (multi-period) + sporadic dynamic of high priority AR_mpPoll.
  • Fig. 21 is equivalent to the previous one but with two attention detections in A R_mprPoll queries.
  • Fig. 22 shows a sporadic RR + ET planning with mode change procedure.
  • messages period hypercycle period
  • a communication method or protocol proposed it is intended to constitute the communications core of a Distributed Real-Time System, providing a set of Communication Services in each of the nodes that They are part of the system. These services allow the operation of the distributed system under a master / slave type transmission scheme, on a bus type topology.
  • Fig. 1 the numbers indicate the order of movement of the messages. This configuration is based on a centralized bus management on the master node.
  • the different dialogues (message exchange) are always initiated by the master (active station) towards a slave node, the latter acting in response to said action (passive station). All dialogues are between the master and a slave (or several, if it is a broadcast message).
  • e and f attention request detection in slave stations and confirmed broadcast
  • the method places more emphasis in order to solve some typical (but not exclusive) problems of master-slave type RTDS. Specifically it allows: to. Reduce high latencies in the detection of an urgent situation of one or more slave nodes typical of a cyclic bus management. b. Avoid low bus efficiency if, in order to solve the previous case, it is decided to increase the relationship between the frequency of consultation and the frequency of the bus hypercycle. c. Only hold the master node responsible for bus planning, allowing it to adopt simple or combined schedules, of type "time-triggered” and "event-triggered", avoiding any type of bus collision.
  • This microcontroller is supposed to be equipped with a UART and allows, as usual, direct access to the serial input / output signals (known as RxD, TxD).
  • RxD serial input / output signals
  • TxD serial input / output signals
  • electronic circuitry hardware of the same. This characteristic is considered very important in order to be able to develop very low cost systems based on this communication method, that is to say systems consisting basically of a microcontroller and a bus transceiver, as can be seen in Fig. 2 .
  • the services offered by a communication system using this method are as detailed below. All the following services are available in the SAP of the bus controller of the master node and are initiated as a request (primitive requesf) from its user. The users of the affected slave nodes only act as a consequence of the received indication (primitive indication) and causing, according to the service, a response (primitive response).
  • SendPP Send Point to Poinf
  • SendPPA Send Point to Point with Acknowledgment
  • a / C this field indicates, at the same time, the type of frame and the node or nodes to which the frame is directed, depending on its value; extra This 2-bit extra field provides additional information to the frame and has different meanings depending on the A / C field.
  • the BA_nPoll service it is used as a sequence number (nseq).
  • the normal or data frame is the one of general use used by the communication system for data transfers between the users of said layer.
  • destination address add ⁇ , sequence number (seq), data length (dlen), command or associated order (cmd)
  • debugging service indication debug
  • data data
  • the content of most of these fields is defined by the user of the request service primitive and, in the rest (chk, EOF ) is defined by the communication system itself.
  • the frame format can be seen in Fig. 4, in which the orientation to the character of the frame can be seen.
  • Byte frame shown in Fig. 5, is reserved for exceptional situations. It consists of a single byte, which must comply with the common characteristics of the first frame byte. Your mp bit must be activated and the accepted values will depend on whether the frame is used internally of the protocol or from the user.
  • the objective of these two peculiarities (a single byte and activated mp) has the following objective:
  • the SingleSlot frame illustrated in Fig. 6 is used to detect, by a brief query, an "affirmative" state of a certain bit (hereinafter bitX or reference bit), in one or more of the slave nodes constituting the bus, without identifying in which of them it is activated. It basically involves sending a frame consisting of one byte, followed by a temporary bus management interval. During this interval, slave nodes can manifest the status of bitX. In the example in this figure, node 1 responds affirmatively.
  • This frame uses two modes of access to the bus, which are defined below: UART mode: Access to the bus is through the reception / sending of characters, using a typical UART.
  • Direct Mode Access to the bus is direct to the TxD and TxDenable (transmission) and RxD (reception) signals, without UART intervention.
  • both the master node and the slave nodes move from operation in UART mode to direct mode (t M2 ).
  • t M3 also called the response window, it is formed by a single response slot, where the slave nodes that have to state an affirmative state of the reference bit, send a dominant pulse within this interval.
  • the master node and the slave nodes go from direct mode to UART mode.
  • the master node terminates the frame at the end of the interval t.
  • the slave node ends before, at the end of the interval t S. This is necessary in order to ensure that the slave node is able to handle the next frame as soon as the master node puts it on the bus.
  • the slave node detects the end of the frame within this interval by a delay initiated locally at the end of the interval t ⁇ of fixed value t 23 , to which it subsequently adds the value t S.
  • the MultiSlot Frame shown in Figs.
  • bitX or reference bit a certain bit in each of the slave nodes constituents of the bus.
  • bitX a certain bit in each of the slave nodes constituents of the bus.
  • bitX a certain bit in each of the slave nodes constituents of the bus.
  • bitX a certain bit in each of the slave nodes constituents of the bus.
  • the initial byte of this frame contains the two usual fields of the other types of frame: AC field and extra field.
  • the A / C field depending on the service, may place special characters that indicate that it is a broadcast frame (to be heard by all nodes) and implicitly indicate the bit over which perform the query (reference bit).
  • the meaning of the extra field will depend on the A / C field.
  • the operation mode of this MultiSlot frame is basically the sending of a byte in UART mode from the master node (see interval ti in figure Fig. 7), followed by an interval (t M2 ) to change to direct mode.
  • the slave nodes must state the status of a certain bitX within their corresponding sub-interval or slot, using the direct mode.
  • the physical layer of the bus must work with dominant / recessive levels.
  • the response with a dominant pulse within the corresponding slot is considered that the reference bit is has the logical value 0.
  • the response at recessive level (without dominant response pulse) is considered that the reference bit has the logical value 1 or that the slave node is disconnected (or without communication capacity due to a malfunction).
  • nodes 1 and N respond affirmatively. This reversal of the bit / signaling ratio with respect to the SingleSlot frame is to take the absence of response as the most unfavorable case.
  • the master node goes from the direct mode to the UART mode and at the end of the latter the frame is terminated.
  • the frame ends earlier in the slave nodes (after the interval t S ).
  • this Fig. 7 corresponds to the concrete solution set forth in claim 16, of pulse train synchronism.
  • the master node For the identification of the different slots of which the temporary treatment window is composed, the master node generates a train of pulses, as shown in Fig. 7. This temporal space is formed by N slots of equal duration. N is the maximum number of nodes (slaves + master) expected in the particular bus configuration. Slots are numbered from Slot 0 to Slot N - ⁇ . Each SLV X slave node corresponds to slot x .
  • Fig. 8 illustrating the MultiSlot frame in asynchronous mode, it is appreciated that said frame is used to query, from the master node, through a brief query, the status ("affirmative” or "negative") of a given bit ( hereinafter bitX or reference bit) in each of the constituent slave nodes of the bus.
  • the slave master interaction procedure is as follows: This frame consists of 4 parts (ti, t M2 , t M3 and t M in Fig. 8.
  • the master node sends a character to the bus in the interval t M2 all nodes (master and slaves) change to direct mode.
  • the slave nodes must state the status of a certain bitX within their corresponding sub-interval or slot, using the direct mode. To do this, the physical layer of the bus must work with dominant / recessive levels.
  • the master node goes from direct mode to UART mode and at the end of this, the frame is terminated. As was already the case in the SingleSlot frame, the frame ends earlier in the slave nodes (after the ts interval).
  • the response with a dominant pulse within the corresponding slot is considered that the reference bit is has the logical value 0.
  • the response at recessive level is considered that the reference bit has the logical value 1 or that the slave node is disconnected (or without communication capacity due to a malfunction).
  • nodes 1 and N respond affirmatively. This reversal of the bit / signaling ratio with respect to the SingleSlot frame is to take the absence of response as the most unfavorable case.
  • Slot 0 does not correspond to any slave node, and its use, reserved, can be used for other possible versions.
  • MultiSlot frame is shown in Fig. 9, with character-oriented response mode. It basically consists of sending a byte from the master node (see interval ti in figure Fig. 9) and then an operating interval in "response" mode to the bus (interval t 3 ). During t 3 , slave nodes must state the status of a certain bitX within its corresponding sub-interval or slot. There are two ways to access the bus: "UART" mode: Access to the bus with the standard character and speed format
  • the first byte of this MultiSlot frame is treated by the normal mode (ti interval).
  • the remaining bytes (response of the slave nodes) are treated by the answer mode
  • interval t 3 (interval t 3 ).
  • the intervals t 2 and t 4 basically have the function of allowing the change of mode on the various nodes of the bus: t 2 to switch from normal mode to response mode, and t 3 to switch from response mode to normal mode, before finishing the MultiSlot frame.
  • the SlotContention frame is shown as well as the operation mode of said contention frame that basically consists of sending a byte in UART mode from the master node (see interval t, in Fig 10), followed of an interval (t M2 ) to change to direct mode.
  • interval t M3 the interval or response window (t M3 ) all slave nodes with an ongoing request for attention try to express it on the bus, of which only the highest priority request fully accesses the bus. The rest are removed, waiting for the completion of the plot.
  • the Interval (t 4 ) allows you to enter the UART operating mode.
  • the master node For the identification of the different slots of which the temporary treatment window is composed, the master node generates a train of pulses, as shown in Fig. 10. This temporal space is formed by 8 slots of equal duration.
  • the priority byte of a request for attention consists of 7 bits [r 6 , ..., r 0 ].
  • the response window has 8 slots or time intervals.
  • the first slot, called sloto exists only for the purpose of facilitating the implementation of the mechanism and does not intervene in the contest.
  • the rest of the slots [slot 1 , ... slot 7 ] are assigned correlatively to one bit of the request byte [r 6 , ..., r 0 ], so that it starts by transmitting the highest bit in only ⁇ weight (bit r 6 ), as can be seen in Fig. 10.
  • the fighting mechanism is carried out in each slot.
  • nodes When several nodes have a request, they put on the bus the bit of their request byte corresponding to the current slot. Of these nodes, those that detect that the slot has adopted the same level that they have sent, will continue fighting in the next slot. The rest, they will have detected a level on the bus contrary to the one sent, withdrawing from the contest process during the rest of the response window. Finally, only one node will be able to set the 7 bits of the request.
  • slaves 2, 1 and 5 have ongoing requests for priority pr f ⁇ na
  • Slave 5 loses the contest in slot-i, so it no longer sends any bit to the bus during the rest of the frame.
  • Slave 1 is the same but in the penultimate slot.
  • Slave 2 is the only one that overcomes the contest by having placed on the bus its full pr f ⁇ ⁇ a ⁇ request (7 bits).
  • the mechanism inherent in this plot requires that the physical layer work with dominant / recessive levels. In each slot, the response at the dominant level is considered a logical "1" and if it is at the recessive level it is considered a logical "0".
  • the process comprises the following steps: 1.
  • the master node SC sends the normal type frame to the bus according to the parameters indicated by the master node user.
  • the content of the cmd field is adopted internally in the service with the value CMDJJDR.
  • the SC of the slave node activates the indication primitive if it receives an error-free normal type frame, with the cmd field containing the CMDJJDR value.
  • the slave node protocol controller will wait indefinitely for the request of the confirmation response primitive from its local user until one of the following cases occurs: a. The user accesses the response primitive with valid parameters. In this case, the local SC sends the corresponding normal type frame, with the same nseq and debug fields as those of the previously received frame. At the end of the transmission of this frame, the local SC of the slave node waits for the detection of a new service. b. A character is detected on the bus. In this case, the local SC of the slave node discards said reception, disables a possible response from its user and waits for the detection of a new service. This prevents the SC from being blocked by an error in the local application.
  • the SC of the master node terminates the service, activating the confirm primitive, when the reception of a normal frame ends, with or without error, or when a time overflow has elapsed (the timer has reached the limit value).
  • a normal frame must be received as indicated in point 3, before the time overflow.
  • the contents of the cmd and debug fields are not checked.
  • the debug field used to identify the type of user to confirm the termination of the service is not checked, since the SC of the master node already knows that value from the parameter initially passed in the service request.
  • a message distribution is exposed on the bus based on a static planning sorted by time (TT - Time Trigger), suitable for transactions between databases.
  • TT - Time Trigger a static planning sorted by time
  • Fig. 12 shows the temporary diagram of access to the bus corresponding to a distributed system where the different nodes have access to the equitable bus, with the same frequency of access to it for the exchange of data.
  • the master node performs a sequence of SendPPUDR services (write / read local buffer) for each slave node, forming a repetitive cycle. This figure shows the return and return message of each transaction. Planning oriented to multiple groups of nodes with different period
  • the DCS layer can solve this situation, creating a bus hypercycle that is the least common multiple of the refresh periods of each subapplication.
  • Fig. 13 shows the time diagram of an example with three groups of nodes: group 1 ⁇ 5,6 ⁇ ; group 2 ⁇ 1 ... 4 ⁇ ⁇ group 3 ⁇ 7 ... F ⁇ .
  • Each of these groups with transmission frequency, with respect to the basic bus frequency f H c, of 3, 2 and 1, respectively.
  • a rate-monotonic priority scheme has been used to solve the coincidence of bus access intervals by more than one group.
  • the vertical arrows in Fig. 13 show the start time of the refresh period of each group or subapplication.
  • each box represents a transaction consisting of a SendPPUDR service (a round trip message).
  • Fig. 14 the simplest solution is presented.
  • the hypercycle is divided into two parts, one for the treatment of TT messages and the other for possible lower priority ET messages.
  • the ET procedure consists in sending an AR_nPoll service from the master node and, if a request is detected, the corresponding query is made to that node by means of a SendPPUDR service.
  • Each Yes in this and in Figs. following comprises the set S ⁇ M, ie frame from master to slave i, and frame from said slave to master, as in Fig. 12.
  • a TT planning with groups of nodes using different refresh rate is considered.
  • An ET zone distributed in small intervals has been reserved throughout the hypercycle. In this way it is possible to maintain a regular periodicity of both the planning groups 1, 2 and 3
  • the ET procedure is the same as the previous case.
  • a request for attention of a slave node is detected in the third ET interval of Figure F.
  • AR_nPoll Once identified the node is consulted with a SendPPUDR service.
  • High priority sporadic TT + ET planning This is to insert requests for attention in planning. This also causes an inevitable overload of the hypercycle in regular operation. It is important to highlight the qualification of sporadic, because otherwise, it would frequently dismantle the TT planning. If it is not sporadic it is better to reserve a fixed bandwidth within the TT planning. Three possible approaches to address these requests are presented: a. Trying to overload the bus hypercycle as little as possible, using AR_evPoll services. b. With node confirmation and consultation service in good condition, through AR_nPoll services. c. Identifying at once the highest priority request on the bus. to. with minimal bus overload (EV_evPoll)
  • FIG. 16 A hypercycle containing a TT schedule is shown in Fig. 16
  • Fig. 17 the same system is presented, but in this case there has been a critical request in the slave nodes Slv1 and Slv2. As you can see, the cycle is lengthened, breaking the times of the TT zone, but the control of the bus is not lost.
  • the master node can decide, depending on the severity of the request and the delay which can cause the hypercycle, attend to it immediately or postpone it to continue with the planning of the hypercycle.
  • the AR_evPoll service occupies very little bus space, but does not detect cases in which a slave node does not respond to the query due to a temporary error in the channel or a malfunction in that node.
  • the nodes are examined at least once per hypercycle in TT transactions. If the non-detection of the request is due to temporary errors in the channel, the request will be detected in the next AR_evPoll service. b. with confirmation of received message and correct node (EV iPoll)
  • EV iPoll This is the system with greater capacity to detect anomalous situations, since the AR_nPoll service interprets the non-reply in said service as an error in the transmission, an error in a node or or a request. Since all of them deserve special attention, this leads to a dialogue of the master node with the affected node (s), as in the previous case (AR_evPoll).
  • Figure 18 shows the bus planning in normal operation.
  • AR_mprPoll If instead of using the AR_evPoll service, AR_mprPoll is used, it has the advantage of the immediate identification of the highest priority request, at the expense of a higher overload on the hypercycle, but less than that offered by the AR_nPoll service.
  • Fig. 20 the hypercycle is shown under normal conditions and in Fig. 21 in the case of two requests. After the first request is detected, a point-to-point service is performed. Then another AR_mpr query is sent, in which a second request is manifested, it is answered and finally another query is made, which does not detect any node, so the planning is continued.
  • the difference between the high and low priority ET set can be established using the priority field (two bits) of the query services.

Landscapes

  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Small-Scale Networks (AREA)

Abstract

L'invention concerne un procédé de communication en série à schéma de fonctionnement de type maître-esclave. Ce procédé est optimisé pour une architecture basée sur un microprocesseur pourvu d'un UART (émetteur-récepteur asynchrone universel) pour chaque noeud, aussi bien maître qu'esclave, ledit noeud maître agissant toujours en tant que station primaire et les noeuds esclaves en tant que stations secondaires. La planification de la voie de communication de cette structure consiste à distribuer des messages circulant par ladite voie, formés en général par un ensemble de groupes de messages de transfert de données. Ledit procédé consiste à utiliser des trames particulières de consultation, de plusieurs types, permettant de détecter à partir du noeud maître, dans des intervalles de temps raisonnables, la ou les demandes actuelles des noeuds esclaves, lesdites trames particulières pouvant être utilisées, dans d'autres schémas de fonctionnement, en tant que mécanisme de base de distribution desdits messages de données, précédant ceux-ci.
PCT/ES2001/000423 2001-11-06 2001-11-06 Protocole de communication en serie a schema de fonctionnement maitre- esclave Ceased WO2003055152A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
PCT/ES2001/000423 WO2003055152A1 (fr) 2001-11-06 2001-11-06 Protocole de communication en serie a schema de fonctionnement maitre- esclave

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
PCT/ES2001/000423 WO2003055152A1 (fr) 2001-11-06 2001-11-06 Protocole de communication en serie a schema de fonctionnement maitre- esclave

Publications (1)

Publication Number Publication Date
WO2003055152A1 true WO2003055152A1 (fr) 2003-07-03

Family

ID=8244390

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/ES2001/000423 Ceased WO2003055152A1 (fr) 2001-11-06 2001-11-06 Protocole de communication en serie a schema de fonctionnement maitre- esclave

Country Status (1)

Country Link
WO (1) WO2003055152A1 (fr)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102007036440A1 (de) * 2007-08-02 2009-02-05 Bayerische Motoren Werke Aktiengesellschaft Verfahren zur Übertragung von Daten
US11380190B2 (en) * 2020-04-30 2022-07-05 Kone Corporation Safety communication in an elevator communication system

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2240865A (en) * 1990-02-06 1991-08-14 Nissan Motor Controlling communications between master and slave stations
US5488693A (en) * 1992-06-24 1996-01-30 At&T Corp. Protocol with control bits and bytes for controlling the order of communications between a master processor and plural slave processors
US5530436A (en) * 1993-06-26 1996-06-25 Motorola, Inc. Method of communications between master unit and slave unit with efficient protocol
EP0728623A1 (fr) * 1995-02-21 1996-08-28 Automobiles Peugeot Procédé de gestion de la transmission de messages sur un réseau de transmission d'un système électronique embarqué à bord d'un véhicule automobile
GB2306240A (en) * 1995-10-14 1997-04-30 Rover Group Multiplexed electrical control systems
EP0862296A2 (fr) * 1997-02-21 1998-09-02 Denso Corporation Système de communication de données et unité de contrÔle électronique utilisée dans celui-ci
US6188314B1 (en) * 1999-02-03 2001-02-13 Trw Inc. Energy distribution and communication system and method utilizing a communication message frame for a multi-device vehicle occupant protection system

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2240865A (en) * 1990-02-06 1991-08-14 Nissan Motor Controlling communications between master and slave stations
US5488693A (en) * 1992-06-24 1996-01-30 At&T Corp. Protocol with control bits and bytes for controlling the order of communications between a master processor and plural slave processors
US5530436A (en) * 1993-06-26 1996-06-25 Motorola, Inc. Method of communications between master unit and slave unit with efficient protocol
EP0728623A1 (fr) * 1995-02-21 1996-08-28 Automobiles Peugeot Procédé de gestion de la transmission de messages sur un réseau de transmission d'un système électronique embarqué à bord d'un véhicule automobile
GB2306240A (en) * 1995-10-14 1997-04-30 Rover Group Multiplexed electrical control systems
EP0862296A2 (fr) * 1997-02-21 1998-09-02 Denso Corporation Système de communication de données et unité de contrÔle électronique utilisée dans celui-ci
US6188314B1 (en) * 1999-02-03 2001-02-13 Trw Inc. Energy distribution and communication system and method utilizing a communication message frame for a multi-device vehicle occupant protection system

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102007036440A1 (de) * 2007-08-02 2009-02-05 Bayerische Motoren Werke Aktiengesellschaft Verfahren zur Übertragung von Daten
DE102007036440B4 (de) * 2007-08-02 2015-07-09 Bayerische Motoren Werke Aktiengesellschaft Verfahren zur Übertragung von Daten
US11380190B2 (en) * 2020-04-30 2022-07-05 Kone Corporation Safety communication in an elevator communication system

Similar Documents

Publication Publication Date Title
US11233750B2 (en) Method and apparatus for allocating transmission opportunities in vehicle network
DE60301752T9 (de) Verfahren zur Überwachung einer Zugriffsablaufsteuerung für ein Kommunikationsmedium einer Kommunikationssteuerung eines Kommunikationssystems
RU2596582C2 (ru) Способ и устройство для адаптируемой к размерам памяти последовательной передачи данных
DE60301767T2 (de) Normalisierung eines Verifizierungsmasses in einer Vorrichtung zur Sprecherverifikation
US10326865B2 (en) Filter or bridge for communications between CAN and CAN-FD protocol modules
US8819327B2 (en) Communication system having a can bus and a method for operating such a communication system
US9298529B2 (en) Indicating internal transmitter errors in a controller area network (CAN)
US9425992B2 (en) Multi-frame and frame streaming in a controller area network (CAN) with flexible data-rate (FD)
EP3599743B1 (fr) Procédé et dispositif pour communiquer des trames de données sur un bus multi-maître
TW201322689A (zh) 操作一通訊裝置的方法
Leen et al. Time-triggered controller area network
US8180940B2 (en) Method and system for transmission of cyclic and acyclic data over a transmission channel that takes into account real-time capability
EP2940935B1 (fr) Dispositif de réseau de zone de contrôleur (CAN) et procédé de commande de trafic CAN
JP6410914B1 (ja) シリアル通信システム
US7284078B2 (en) Deterministic field bus and process for managing same such that when transmissions from one subscriber station are enabled transmissions from other subscriber stations are disabled
WO2003055152A1 (fr) Protocole de communication en serie a schema de fonctionnement maitre- esclave
Hafeez et al. State of the art survey on comparison of can, flexray, lin protocol and simulation of lin protocol
JP2004280304A (ja) フィールドバスシステム及び通信方法並びにマスタ及びスレーブ
KR20200049577A (ko) 차량 네트워크에서 우선 전송 기회를 할당하는 방법 및 장치
US6987776B1 (en) Multiplex communication method, the device and the system thereof
US10728064B2 (en) Interface circuit
Bell Network protocols used in the automotive industry
Wey et al. Enhancement of Controller Area Network (CAN) bus arbitration mechanism
JP4107110B2 (ja) フィールドバスシステム及び接続確認方法並びにマスタ
Kammerer TTCAN

Legal Events

Date Code Title Description
AK Designated states

Kind code of ref document: A1

Designated state(s): US

AL Designated countries for regional patents

Kind code of ref document: A1

Designated state(s): AT BE CH CY DE DK ES FI FR GB GR IE IT LU MC NL PT SE TR

121 Ep: the epo has been informed by wipo that ep was designated in this application
122 Ep: pct application non-entry in european phase